Large-Scale Nonlinear Lumped and Integrated Field Simulations of Top-Orthogonal-to-Bottom-Electrode CMUT Architectures

Capacitive micromachined ultrasonic transducers (CMUTs) promise many advantages over traditional piezoelectric transducers such as the potential to construct large, cost-effective 2-D arrays. To avoid wiring congestion issues associated with fully wired arrays, top-orthogonal-to-bottom electrode (TOBE) CMUT array architectures have proven to be a more practical alternative, using only <inline-formula> <tex-math notation="LaTeX">$2N$ </tex-math></inline-formula> wires for an <inline-formula> <tex-math notation="LaTeX">$N \times N$ </tex-math></inline-formula> array. Optimally designing a TOBE CMUT array is a significant challenge due to the range of parameters from the device level up to the operating conditions of the entire array. Since testing many design variations can be prohibitively expensive, a simulation approach accounting for both the small and large-scale array characteristics of TOBE arrays is essential. In this paper, we demonstrate large-scale TOBE CMUT array simulations using a nonlinear CMUT lumped-circuit model. We investigate the performance of the array with different CMUT design parameters and array operating conditions. These simulated results are then compared with measurements of TOBE arrays fabricated using a sacrificial release process.